(a) Field of the Invention
The present invention relates to an ultra-thin speaker, and more particularly to an ultra-thin speaker with a structure of conducting heat of a heat source to a metal upper casing by a thermal conduction to increase a heat dissipating area.
(b) Description of the Related Art
As 3C electronic devices such as mobile phones (or handsets), MP3 players, notebook computers (NB), liquid crystal displays (LCD), and personal digital assistants (PDA) have an enhanced operating performance, a compact design, and a multimedia function, the 3C electronic devices generally adopt an appropriate mini speaker for an audio output interface.
Speaker is an electro-acoustic device for converting electronic signals into audio signals, and producing a repulsion with a magnetic member to provide a piston-like action after a voice coil is electrically conducted, such that a vibrating membrane installed in front of the magnetic member is pushed accordingly to radiate sound waves in front of the vibrating membrane in all directions to the outside. However, the operation of the voice coil and the magnetic member may cause a high temperature easily, and the high temperature issue has become an inevitable drawback.
Since present existing consumer products become smaller and smaller, the electronic or plastic components installed inside the products are very close to the position of the speaker, therefore the piston action between the voice coil and the magnetic member will produce a high temperature after the voice coil of the speaker is electrically conducted. The high temperature not just affects the sound quality and performance of the speaker, but also affects the operation of adjacent components of the electronic device. Even worse, the continuously increasing temperature may burn the voice coil or damage the electronic device, or may even cause accidents.
The aforementioned speaker body has a poor heat dissipating effect, and the poor heat dissipation may burn the voice coil. The high temperature also affects the existing sound quality and performance. Therefore, manufacturers have provided solutions to overcome the heat dissipation issue of the voice coil. These solutions mainly include an improved convection of air, an improved structure of a speaker body, and an improved metal heat dissipating material.
As disclosed in R.O.C. Pat. No. 00305509, a dust-resisting cover of a speaker is made of a metal material instead, and the dust-resisting cover is installed to an opening of a voice coil directly, such that the heat produced by the voice coil can be discharged from the metal dust-resisting cover.
In an improved speaker assembly as disclosed in R.O.C. Pat. No. 00431741, external cold air is introduced into a gap between a voice coil and a magnetic member, and heat is discharged to the outside during the operation the speaker in order to avoid overheat of the voice coil.
As disclosed in R.O.C. Pat. No. 00453601, a circular heat sink is installed onto a voice coil directly and wrapped by a magnetic member for dissipating a high-temperature heat produced by the voice coil and the magnetic member.
As disclosed in R.O.C. Pat. No. M249394 (with a foreign counterpart P.R.C. Pat. No. ZL02288716.4), a heat dissipating plate is adhered onto a voice coil and a rear end of a magnetic member for discharging hot air produced in the operation of the speaker to avoid overheat of the voice coil.
In P.R.C. Pat. No. ZL200620014749.2, a circular heat sink similar to a washer (which is a magnetic conducting plate installed on a speaker body) is disclosed, wherein the heat sink is a serrated structure capable of expediting the dissipation of heat energy of the voice coil.
In P.R.C. Pat. No. ZL200720000787.7, a concave heat dissipating device is disclosed, and a magnetic yoke (U-shaped iron) under a magnet is installed in the concave heat dissipating device, and a thermal paste is applied to connect the magnetic yoke and the concave heat dissipating device securely, such that when the heat of the speaker body is conducted to the magnetic yoke, heat can be discharged quickly and directly to the outside through the external concave heat dissipating device.
In P.R.C. Pat. No. ZL99217826.6, a plurality of heat dissipating holes are formed around the periphery of a magnetic yoke (T-shaped iron), and a circular hole is formed on a magnetic pillar, and a plurality of fins are installed at the bottom of the magnetic yoke for improving the heat dissipating efficiency.
In P.R.C. Pat. No. ZL200520053787.4, the magnetic conduction of the original magnetic yoke (U-shaped iron) is separated from the function of fixing the magnetic member. By changing the material of the magnetic yoke from the traditional iron material to a lightweight material, we can reduce the weight of the speaker and achieve the effects of dissipating heat. Meanwhile, a heat sink is installed outside the magnetic yoke to improve the heat dissipating efficiency.
In P.R.C. Pat. No. ZL200420083784.0, a structure of an internal magnetic speaker body is disclosed to improve the heat dissipating efficiency of the speaker body and enhance the sound quality of base. In the improved internal magnetic speaker body structure, a serrated heat sink is installed outside a magnetic yoke (U-shaped iron) for conducting the heat of a voice coil to the heat sink through the magnetic yoke. Meanwhile, the heat sink includes an open groove formed in the circumferential direction and extended into an air chamber behind the vibrating membrane through an opening formed on a support frame of the speaker, such that the resonance frequency point F0 can be minimized without using an additional speaker enclosure to achieve the effect of enhancing the sound quality of base.
However, the methods or structures for solving the heat dissipation problem of the voice coil in accordance with the aforementioned prior arts still have a drawback of having a too-large volume that cannot fit in the limited space of the thin speaker.
In R.O.C. Pat. No. M352209 (with a foreign counterpart P.R.C. Pat. No. ZL2008201353250) issued to the inventor of the present invention, the structure of a thin mini speaker heat dissipating device is disclosed, wherein a metal plate is installed around a U-shaped magnetic yoke, such that the heat produced by the magnetic yoke can be conducted to the outside. Although this structure provides a function of dissipating heat to a certain extent, the metal plate must be installed in the space inside upper and lower casings, so that the heat dissipating area is limited. Furthermore, the overall thickness is still several millimeters, and such thickness still cannot meet the requirements of present electronic products such as mobile phones.
In view of the foregoing shortcomings of the prior arts, the inventor of the present invention further improves the heat dissipating efficiency and the thickness of the thin mini speakers in accordance with the present invention.